reset for mitt romney, or so they hope coming off a bad weeks, unleashing a new attack on president obama, regarding the chaos in the east. >>> and fighting breast cancer, what they hope can be a new breakthrough in a new roadmap to more effective teaching. >>> and education nation summit, what is coming to just about every school in the country. question is, are teachers and students ready for what is on the way. >>> a broken heart, could it really be fatal? tonight, the doctors who say yes and warn that women have the most to worry about. >>> and the panda, why it is proving so difficult to save these animals. >>> this is nbc nightly news with brian williams. >>> good evening, if the race for president seems to have an urgency not fully supported by the calendar, then think of it this way. there are roughly a thousand hours to go before the election. every day and moment counts for the incumbent president and the man trying to unseat him. while both men have squared off in separate interviews over the last 24 hours, the first debate is still at least week away. and coming off a bad week